Confining features for mode shaping of lasers and coupling with silicon photonic components

ABSTRACT

A laser structure, including: a dielectric matrix formed of a first material; a laser source formed within the dielectric matrix and formed of a semiconductor material; and a plurality of side confining features formed within the dielectric matrix and extending parallel to and along a length of the laser source. The plurality of side confining features are formed of the semiconductor material.

BACKGROUND

The present disclosure generally relates to photonic integratedcircuits, and more particularly, to confining features for mode shapingof III-V lasers and enhanced coupling with silicon (Si) photoniccomponents.

Silicon photonics is becoming a mainstream data-transmission solutionfor next-generation data centers, high-performance computers, and manyemerging applications. Silicon-based photonic integrated circuits (PICs)offer the promise of low-cost and high-volume solutions fornext-generation, high speed, energy-efficient optical interconnects.While remarkable advances have been achieved at both the component andsystem level, on-chip integration of low cost and power efficient lasersources (e.g., III-V semiconductor lasers) onto a silicon-based PICremains a significant challenge. For example, efficient coupling betweenIII-V semiconductor lasers and silicon photonic waveguides remains asignificant issue due to the mode profile mismatch between III-Vsemiconductor lasers and silicon photonic waveguides.

SUMMARY

Generally, the present disclosure is directed to photonic integratedcircuits, and more particularly, to confining features for mode shapingof III-V lasers and enhanced coupling with silicon (Si) photoniccomponents. One illustrative laser structure disclosed herein includes:a dielectric matrix formed of a first material; a laser source formedwithin the dielectric matrix and formed of a semiconductor material; anda plurality of side confining features formed within the dielectricmatrix and extending parallel to and along a length of the laser source,the plurality of side confining features formed of the semiconductormaterial.

Another illustrative laser structure disclosed herein includes: adielectric matrix formed of a first material; a laser source formedwithin the dielectric matrix and comprising a semiconductor material;and a plurality of vertical confining features formed within thedielectric matrix and extending parallel to and along a length of thelaser source, the plurality of vertical confining features comprisingthe semiconductor material.

An illustrative laser system disclosed herein includes: a laser source;and a waveguide optically coupled to the laser source, wherein the lasersource comprises: a dielectric matrix formed of a first material; alaser source formed within the dielectric matrix and comprising asemiconductor material; and a plurality of confining features formedwithin the dielectric matrix and extending parallel to and along alength of the laser source, the plurality of confining featurescomprising the semiconductor material, wherein the plurality ofconfining features are formed on at least one of a side, top, or bottomof the laser source, and wherein the plurality of confining features areconfigured to adjust a size and profile of a mode of the laser source tomatch a mode of the waveguide.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numerals identify like elements.

FIG. 1 depicts a cross-sectional view of a III-V semiconductor laserstructure with symmetrically arranged side confining features accordingto various embodiments of the disclosure.

FIG. 2 is a plan view of the laser core and side confining features ofFIG. 1 according to various embodiments of the disclosure.

FIG. 3 depicts a cross-sectional view of another III-V semiconductorlaser structure including side confining features according to variousembodiments of the disclosure.

FIG. 4 is a plan view of the laser core and side confining features ofFIG. 3 according to various embodiments of the disclosure.

FIG. 5 depicts a cross-sectional view of another III-V semiconductorlaser structure including side confining features according to variousembodiments of the disclosure.

FIG. 6 is a plan view of the laser core and side confining features ofFIG. 5 according to various embodiments of the disclosure.

FIG. 7 depicts a cross-sectional view of another III-V semiconductorlaser structure including side confining features according to variousembodiments of the disclosure.

FIG. 8 is a plan view of the laser core and side confining features ofFIG. 7 according to various embodiments of the disclosure.

FIG. 9 depicts a cross-sectional view of another III-V semiconductorlaser structure including side confining features according to variousembodiments of the disclosure.

FIG. 10 is a plan view of the laser core and side confining features ofFIG. 9 according to various embodiments of the disclosure.

FIG. 11 depicts a cross-sectional view of another III-V semiconductorlaser structure including side confining features according to variousembodiments of the disclosure.

FIG. 12 depicts a cross-sectional view of a III-V semiconductor laserstructure including vertical confining features according to variousembodiments of the disclosure.

FIG. 13 is a side perspective view of the laser core and verticalconfining features of FIG. 12 according to various embodiments of thedisclosure.

FIG. 14 depicts a cross-sectional view of another III-V semiconductorlaser structure including vertical confining features according tovarious embodiments of the disclosure.

FIG. 15 is a side perspective view of the laser core and verticalconfining features of FIG. 14 according to various embodiments of thedisclosure.

FIG. 16 depicts a cross-sectional view of another III-V semiconductorlaser structure including vertical confining features according tovarious embodiments of the disclosure.

FIG. 17 is a side perspective view of the laser core and verticalconfining features of FIG. 16 according to various embodiments of thedisclosure.

FIG. 18 depicts a cross-sectional view of another III-V semiconductorlaser structure including vertical confining features according tovarious embodiments of the disclosure.

FIG. 19 is a side perspective view of the laser core and verticalconfining features of FIG. 18 according to various embodiments of thedisclosure.

FIG. 20 depicts a cross-sectional view of another III-V semiconductorlaser structure including vertical confining features according tovarious embodiments of the disclosure.

FIG. 21 depicts a cross-sectional view of the laser core and verticalconfining features of FIG. 20 according to various embodiments of thedisclosure.

FIGS. 22-28 depict cross-sectional views of processes for forming aIII-V semiconductor laser structure with side confining featuresaccording to various embodiments of the disclosure.

FIGS. 29-33 depict cross-sectional views of processes for forming aIII-V semiconductor laser structure with vertical confining featuresaccording to various embodiments of the disclosure.

While the subject matter disclosed herein is susceptible to variousmodifications and alternative forms, specific embodiments thereof havebeen shown by way of example in the drawings and are herein described indetail. It should be understood, however, that the description herein ofspecific embodiments is not intended to limit the disclosure to theparticular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the disclosure as defined by the appendedclaims.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part thereof, and in which is shown by way ofillustration specific exemplary embodiments in which the presentteachings may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thepresent teachings, and it is to be understood that other embodiments maybe used and that changes may be made without departing from the scope ofthe present teachings. The following description is, therefore, merelyillustrative.

The words and phrases used herein should be understood and interpretedto have a meaning consistent with the understanding of those words andphrases by those skilled in the relevant art. No special definition of aterm or phrase, i.e., a definition that is different from the ordinaryand customary meaning as understood by those skilled in the art, isintended to be implied by consistent usage of a term or phrase herein.To the extent that a term or phrase is intended to have a specialmeaning, i.e., a meaning other than that understood by skilled artisans,such a special definition will be expressly set forth in thespecification in a definitional manner that directly and unequivocallyprovides the special definition for the term or phrase.

The present disclosure generally relates to III-V semiconductor lasersintegrated with various configurations of side and/or vertical confiningfeatures. The laser core (lasing medium) and the confining features maybe formed of III-V semiconductor materials with a high refractive indexand may be embedded in a metamaterial (e.g., a dielectric matrix) havinga refractive index lower than that of the laser core and confiningfeatures. The side and/or vertical confining features may be formed insymmetric and/or asymmetric configurations depending, for example, onthe geometry and mode shape of the waveguide to which the laser core iscoupled (e.g., a silicon (Si) inverse taper waveguide). The side and/orvertical confining features may be selected to adjust laser mode sizeand profile to reduce mode mismatch between III-V semiconductor lasersand waveguides, increasing coupling efficiency.

Referring now to FIG. 1 , there is illustrated a cross-sectional view ofa III-V semiconductor laser structure 10 (hereafter III-V laser 10)according to embodiments. As shown, the III-V laser 10 may include alaser core 12 formed of a III-V semiconductor material with a highrefractive index (e.g., refractive index of >2.0) and embedded in adielectric matrix 14 formed of a material having a refractive index thatis lower than that of the laser core 12. According to embodiments, thelaser core 12 may be formed of a III-V semiconductor material such asindium gallium arsenide phosphide (InGaAsP). Other suitable III-Vsemiconductor materials may also be used to form the laser core 12including, for example, InCaAs, InCaASN, GaAsSb, AlGaAs, or GaAs. Thedielectric matrix 14 may be formed of doped indium phosphide (InP) orother suitable materials (e.g., InAs and InSb).

The dielectric matrix 14 may be formed between n- and p-doped layers 16,18 of InP or other suitable materials (e.g., InAs and InSb). The portionof the dielectric matrix 14 adjacent the n-doped layer 16 of InP mayinclude an n-doped section 20 of InP formed between p-doped sections 22,24 of InP. The portion of the dielectric matrix 14 adjacent the p-dopedlayer 18 of InP may include a p-doped section 26 of InP formed betweenn-doped sections 28, 30 of InP. N-type dopants may include but are notlimited to; phosphorous (P), arsenic (As), antimony (Sb), and p-typedopants may include but are not limited to: boron (B), indium (In) andgallium (Ga).

According to embodiments, a set of one or more side confining features40 may be formed adjacent the laser core 12. As shown in FIG. 1 , forexample, a plurality of symmetrically-arranged side confining features40 may be formed laterally adjacent the laser core 12 in the p-dopedsections 22, 24 of InP. According to embodiments, the side confiningfeatures 40 may be formed of the same high refractive index III-Vsemiconductor material as the laser core (e.g., InGaAsP). Other highrefractive index III-V semiconductor materials such as InCaAs, InCaASN,GaAsSb, AlGaAs, or GaAs may also be used to form the side confiningfeatures 40. In some embodiments, the laser core 12 and the sideconfining features 40 may be formed of different III-V semiconductormaterials. The plurality of symmetrically-arranged side confiningfeatures 40 formed in the p-doped sections 22, 24 of InP on each side ofthe laser core 12 may have the same pitch and duty cycle. The sideconfining features 40 may be formed at the same time as the laser core12 and, according to embodiments, may have the same height 40H.

According to embodiments, the side confining features 40 (and other sideconfining features 40 described hereinbelow) may be configured to adjustthe mode size and profile of the III-V laser 10 to reduce mode mismatchbetween the III-V laser 10 and a waveguide of a photonic integratedcircuit. For example, as shown in FIG. 1 , the side confining featuresmay be configured for use with an inverse tapered Si waveguide 52 of aSi-based photonic integrated circuit 50.

A plan view of the side confining features 40 and the laser core 12 ofFIG. 1 is depicted in FIG. 2 . According to embodiments, referring toFIGS. 1 and 2 , the side confining features 40 may be formedsymmetrically on opposing sides of the laser core 12 in the p-dopedsections 22, 24 of InP. The laser core 12 may have a width 12W of about1 μm to about 5 μm and a height 12H of about 50 nm to about 300 nm. Theside confining features 40 may have a height 40H of about 50 nm to about300 nm and a width 40W of about 50 nm to about 1 μm. In general, thewidth 40W of the side confining features 40 is less than the width 12Wof the laser core 12. The side confining features 40 in the p-dopedsections 22, 24 of InP may be separated from each other by a distance40S. The separation distance 40S between adjacent side confiningfeatures 40 may be about 50 nm to about 1 μm. The separation distance12S between the laser core 12 and the adjacent side confining features40 may be about 50 nm to 1 μm.

As depicted in FIG. 2 , the side confining features 40 in the p-dopedsections 22, 24 of InP may extend parallel to, and along a length of,the laser core 12 and may have a length 40L that is less than or equalto the length 12L of the laser core 12. In this embodiment and any ofthe other embodiments described herein as including side confiningfeatures 40, the distal end 12E of the laser core 12 may be aligned withthe distal end 40E of each of the side confining features 40. Thisalignment ensures that the side confining features reshape the mode ofthe III-V laser 10 towards the end 12E of the gain layer (laser core12). However, some slight offsets may be allowed in practice (e.g., theends 40E of the side confining features 40 may be located slightlybefore or slightly after the end 12E of the laser core).

According to embodiments, the side confining features 40 may have alength 40L from about 10 μm to about 10 mm. In general, according to anyof the embodiments including side confining features 40 describedherein, the number and/or configuration (e.g., height, width, length) ofthe side confining features 40, and/or the placement of the sideconfining features 40 relative to the laser core 12 and relative to eachother (e.g., separation distances 40S, 12S), may vary according toapplication and may be modified as necessary to address the modemismatch between the III-V laser 10 and a waveguide or other componentof a photonic integrated circuit.

Additional embodiments of the III-V laser 10 may include a set of one ormore asymmetrically-arranged side confining features 40. For example, asdepicted in FIGS. 3 and 4 , the number of side confining features 40formed on each side of the laser core 12 may vary. In this example,three side confining features 40 may be formed in the p-doped section 22of InP, while two side confining features 40 may be been formed in thep-doped section 24 of InP, where all of the side confining features 40may have the same height 40H, length 40L, width 40W, and separationdistance 40S.

In other embodiments, the number, configuration, and/or placement of theside confining features 40 may vary on each side of the laser core 12.For example, in FIGS. 5 and 6 , two side confining features 40 may beformed in the p-doped section 22 of InP, each having a height 40H, afirst width 40W₁, and a first separation distance 40S₁, while three sideconfining features 40 may be formed in the p-doped section 24 of InP,each having a height 40H, a second width 40W₂, where 40W₂>40W₁, and asecond separation distance 40S₂. In this example, the spacing 40S₂between the side confining features 40 in the p-doped section 24 of InPmay be different (e.g., smaller) than the spacing 40S₁ between the sideconfining features 40 in the p-doped section 22 of InP. To this extent,the asymmetrically-arranged side confining features 40 may be describedas having a different pitch and duty cycle on each side of the lasercore 12.

A further embodiment of the III-V laser 10 with an asymmetricalarrangement of side confining features 40 is depicted in FIGS. 7 and 8 .As shown, the width and separation distances of the side confiningfeatures 40 in one or both of the p-doped sections 22, 24 of InPadjacent the laser core 12 may vary.

In the above-described embodiments, all of the side confining features40 may have the same height 40H and length 40L. In other embodiments,however, as depicted in FIGS. 9 and 10 , the side confining features 40may have different heights and/or lengths. For example, one or more ofthe side confining features 40 in the p-doped sections 22, 24 of InP mayhave a height 40H₁ and length 40L₁, while one or more of the other sideconfining features 40 in the p-doped sections 22, 24 of InP may have adifferent height 40H₂ and length 40L₂.

FIG. 11 depicts a III-V laser 10 with multi-layer side confiningfeatures 40 according to embodiments. For example, FIG. 11 depicts theIII-V laser 10 of FIG. 1 with additional side confining features 40formed in the n-doped sections 28, 30 of InP located below and to thesides of the laser core 12. As shown, the side confining features 40formed in the n-doped sections 28, 30 of InP may have the sameconfiguration/arrangement as the side confining features 40 formed inthe p-doped sections 22, 24 of InP. However, in general, the sideconfining features 40 formed in the p-doped sections 22, 24 of InPand/or in the n-doped sections 28, 30 of InP may be configured/arrangedin accordance with any of the embodiments described herein.

Referring to FIGS. 12 and 13 , according to additional embodiments, theIII-V laser 10 may include a set of one or more vertical confiningfeatures 60 formed adjacent (e.g., vertically above and/or below) thelaser core 12. For example, FIGS. 12 and 13 depict an embodimentincluding a plurality of vertical confining features 60 formed directlyabove the laser core 12 in the n-doped section 20 of InP. As with theside confining features 40, the vertical confining features 60 may beformed of the same high refractive index semiconductor material as thelaser core 12 (e.g., InGaAsP) or may be formed of other suitable highrefractive index III-V semiconductor materials including, for example,InCaAs, InCaASN, GaAsSb, AlGaAs, or GaAs. In some embodiments, the lasercore 12 and the vertical confining features 60 may be formed ofdifferent III-V semiconductor materials. The vertical confining features60 may be formed at the same time as the laser core 12 and, according toembodiments, may have the same height 60H. In addition, the verticalconfining features 60 may be used in conjunction with any of theembodiments of side confining features 40 described herein (e.g., asshown in phantom in FIG. 12 ) or may be used without side confiningfeatures 40.

A side view of the vertical confining features 60 and the laser core 12of FIG. 12 is depicted in FIG. 13 . According to embodiments, the lasercore 12 may have a width 12W of about 1 μm to about 5 μm and a height12H of about 50 nm to about 300 nm. The vertical confining features 60may have a height 60H of about 5 nm to about 200 nm and a width 60Wcorresponding to (e.g., the same as) the width 12W of the laser core 12(e.g., of about 50 nm to about 1 μm). In general, the height 60H of thevertical confining features 60 may be less than the height 12H of thelaser core 12. As shown, the vertical confining features 60 may beseparated by a distance 60S of about 5 nm to about 50 nm, which may bethe same as or different than the separation distance 12S between thelower-most vertical confining feature 60 and the laser core 12. Theseparation distance 12S between laser core 12 and adjacent verticalconfining feature 60 may be about 5 nm to about 50 nm. In someembodiments, the vertical confining features 60 may have differentwidths 60W or widths different than the width 12W of the laser core 12.

As depicted in FIG. 13 , the vertical confining features 60 may extendparallel to, and along a length of, the laser core 12 and may have alength 60L that is less than or equal to the length 12L of the lasercore 12. For example, according to embodiments, the vertical confiningfeatures 60 may have a length 60L from about 10 μm to about 10 mm. Inthis embodiment and any of the other embodiments described herein asincluding vertical confining features 60, the distal end 12E of thelaser core 12 may be aligned with the distal end 60E of each of thevertical confining features 60. In general, according to any of theembodiments including vertical confining features 60 described herein,the number and/or configuration (e.g., height, width, length) of thevertical confining features 60, and/or the placement of the verticalconfining features 60 relative to the laser core 12 and relative to eachother (e.g., separation distances 60S, 12S), may vary according toapplication and may be modified as necessary to address the modemismatch between the III-V laser 10 and the waveguide or other componentof a photonic integrated circuit.

Additional embodiments of the III-V laser 10 with vertical confiningfeatures 60 are depicted in FIGS. 14-21 . For example, in FIGS. 14 and15 , vertical confining features 60 with the same height 60H and width60W may be formed in the p-doped section 26 of InP directly below thelaser core 12, rather than in the n-doped section 20 directly above thelaser core 12 as in FIGS. 12 and 13 . Further, as depicted in FIGS. 16and 17 , a symmetrical arrangement of vertical confining features 60with the same height 60H and width 60W may be formed both above andbelow the laser core 12 in the n-doped section 20 and p-doped section26, respectively. In this symmetrical example, the vertical confiningfeatures 60 formed above and below the laser core 12 may have the samespacings 60S and 12S.

As depicted in FIGS. 18 and 19 , vertical confining features 60 with thesame width, but different heights 60H₁, 60H₂ may be formed in then-doped section 20 above the laser core 12. As further depicted in FIGS.20 and 21 , the number, spacing, and/or height of the vertical confiningfeatures 60 formed above and below the laser core 12 may vary. Ingeneral, the number, spacing, placement, and/or configuration of thevertical confining features 60 relative to the laser core 12 may varyaccording to application and may be modified as necessary to addresslaser mode mismatch.

An illustrative process for forming a III-V laser 10 with side confiningfeatures 40 is depicted in FIGS. 22-28 .

FIG. 22 depicts a semiconductor substrate 100 that includes an undopedlayer 102 of indium phosphide (InP) overlaying a p-doped layer 104 ofInP. As shown in FIG. 23 , one or more doping processes 106 (e.g., ionimplantation) may be performed to form an n-doped section 108 of InP, ann-doped section 110 of InP, and a p-doped section 112 of InP between then-doped sections 108, 110 of InP. After the doping, as depicted in FIG.24 , a layer 114 of InGaAsP may be formed (e.g., via epitaxy) atop thedoped sections 108, 110, 112 of InP.

FIG. 25 depicts the structure of FIG. 24 after one or moremasking/etching steps have been performed to selectively remove portionsof the layer 114 of InGaAsP. Comparing FIG. 25 to FIG. 1 , it can beseen that the remaining portion 116 of the layer 114 of InGaAsPcorresponds to the laser core 12 and the remaining portions 118 of thelayer 114 of InGaAsP corresponds to the side confining features 40 ofthe III-V laser 10 depicted in FIG. 1 .

FIG. 26 depicts the structure of FIG. 25 after an undoped layer 120 ofindium phosphide (InP) has been formed (e.g., by epitaxy) over theremaining portions 116, 118 of the layer 114 of InGaAsP and over thedoped sections 108, 110, 112 of InP. As shown in FIG. 27 , one or moredoping processes 122 (e.g., ion implantation) may be performed to form ap-doped section 124 of InP, a p-doped section 126 of InP, and an n-dopedsection 128 of InP between the p-doped sections 124, 126 of InP. FIG. 28depicts the structure of FIG. 27 after an n-doped layer 130 of InP hasbeen formed over the doped sections 124, 126, 128 of InP.

An illustrative process for forming a III-V laser 10 with verticalconfining features 60 is depicted in FIGS. 29-33 .

FIG. 29 depicts the structure of FIG. 24 after one or moremasking/etching steps have been performed to selectively remove portionsof the layer 114 of InGaAsP. Comparing FIG. 29 to FIG. 1 , it can beseen that the remaining portion 116 of the layer 114 of InGaAsPcorresponds to the laser core 12 of the III-V laser 10.

FIG. 30 depicts the structure of FIG. 29 after an undoped layer (notshown) of InP has been formed (e.g., by epitaxy) over the remainingportion 116 of the layer 114 of InGaAsP and over the doped sections 108,110, 112 of InP and subsequently doped via one or more doping processes132 (e.g., ion implantation). This step forms a p-doped section 134 ofInP, a p-doped section 136 of InP, and an n-doped section 138 of InPbetween the p-doped sections 134, 136 of InP.

FIG. 31 depicts the structure of FIG. 30 after several additionalprocesses have been performed. One or more masking/etching steps havebeen performed to selectively remove a portion of the n-doped section138 of InP. A layer 140 of InGaAsP was then formed (e.g., via epitaxy)over the remaining n-doped section 138 of InP.

FIG. 32 depicts the structure of FIG. 31 after several additionalprocesses have been performed. After forming a layer 142 of n-doped InPover the layer 140 of InGaAsP, another layer 144 of InGaAsP has beenformed over the layer 142 of n-doped InP.

FIG. 33 depicts the structure of FIG. 32 after several additionalprocesses have been performed. After forming a layer 146 of n-doped InPover the layer 144 of InGaAsP, a layer 148 of n-doped InP has beenformed over the doped sections 134, 136, 146. Comparing FIG. 33 to FIG.12 , it can be seen that the remaining portion 116 of the layer 114 ofInGaAsP corresponds to the laser core 12 and the layers 142, 144 ofInGaAsP corresponds to the vertical confining features 60 of the III-Vlaser 10 depicted in FIG. 12 .

The use of side confining features and/or vertical confining features ina III-V laser increases the coupling efficiency between the III-V laserand a waveguide of a photonic integrated circuit (e.g., an inversetapered Si waveguide of an Si-based photonic integrated circuit). Theside confining features and/or vertical confining features may beselectively configured as necessary to adjust the mode size of the III-Vlaser (e.g., along a lateral direction) to better match the mode size ofthe waveguide, leading to improved coupling efficiency.

The method as described above is used in the fabrication of photonicintegrated circuit (PIC) chips. The resulting PIC chips can bedistributed by the fabricator in raw wafer form (that is, as a singlewafer that has multiple unpackaged chips), as a bare die, or in apackaged form. In the latter case the chip is mounted in a single chippackage (such as a plastic carrier, with leads that are affixed to amotherboard or other higher level carrier) or in a multichip package(such as a ceramic carrier that has either or both surfaceinterconnections or buried interconnections). In any case the chip isthen integrated with other chips, discrete circuit elements, and/orother signal processing devices as part of either (a) an intermediateproduct, such as a motherboard, or (b) an end product. The end productcan be any product that includes integrated circuit chips, ranging fromtoys and other low-end applications to advanced computer products havinga display, a keyboard or other input device, and a central processor.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. For example, the process steps set forth above may beperformed in a different order. Furthermore, no limitations are intendedto the details of construction or design herein shown, other than asdescribed in the claims below. It is therefore evident that theparticular embodiments disclosed above may be altered or modified andall such variations are considered within the scope and spirit of thedisclosure. Note that the use of terms, such as “first,” “second,”“third” or “fourth” to describe various processes or structures in thisspecification and in the attached claims is only used as a shorthandreference to such steps/structures and does not necessarily imply thatsuch steps/structures are performed/formed in that ordered sequence. Ofcourse, depending upon the exact claim language, an ordered sequence ofsuch processes may or may not be required. Accordingly, the protectionsought herein is as set forth in the claims below.

1. A laser structure, comprising: a matrix formed of a first material; alaser source formed within the matrix and comprising a second, differentmaterial; and a plurality of side confining features formed within thematrix and extending parallel to and along a length of the laser source,the plurality of side confining features comprising the second material.2. The laser structure of claim 1, wherein the first material has arefractive index lower than a refractive index of the second material.3. The laser structure of claim 1, wherein the first material comprisesa dielectric material.
 4. The laser structure of claim 1, wherein thesecond material comprises a III-V semiconductor material.
 5. The laserstructure of claim 4, wherein the second material comprises indiumgallium arsenide phosphide (InGaAsP), and wherein the first materialcomprises indium phosphide (InP).
 6. The laser structure of claim 1,wherein the plurality of side confining features comprises: a first setof side confining features formed within the matrix and extendingparallel to and along a length of a first side of the laser source; anda second set of side confining features formed within the matrix andextending parallel to and along a length of a second, opposite side ofthe laser source.
 7. The laser structure of claim 6, wherein the firstset of side confining features and the second set of side confiningfeatures are arranged symmetrically relative to the laser source.
 8. Thelaser structure of claim 6, wherein the first set of side confiningfeatures and the second set of side confining features are arrangedasymmetrically relative to the laser source.
 9. The laser structure ofclaim 1, wherein the laser source is formed in a region of the matrix ofa first doping type and wherein the plurality of side confining featuresare formed in regions of the matrix of a second doping type.
 10. A laserstructure, comprising: a matrix formed of a first material; a lasersource formed within the matrix and comprising a second, differentmaterial; and a plurality of vertical confining features formed withinthe matrix and extending parallel to and along a length of the lasersource, the plurality of vertical confining features comprising thesecond material.
 11. The laser structure of claim 10, wherein the firstmaterial has a refractive index lower than a refractive index of thesecond material.
 12. The laser structure of claim 10, wherein the secondmaterial is a III-V semiconductor material.
 13. The laser structure ofclaim 12, wherein the second material comprises indium gallium arsenidephosphide (InGaAsP), and wherein the first material comprises indiumphosphide (InP).
 14. The laser structure of claim 10, wherein theplurality of vertical confining features are formed in the matrix as oneof: vertically above the laser source; vertically below the lasersource; and vertically above and below the laser source.
 15. The laserstructure of claim 14, wherein the plurality of vertical confiningfeatures are arranged symmetrically relative to the laser source. 16.The laser structure of claim 14, wherein the plurality of verticalconfining features are arranged asymmetrically relative to the lasersource.
 17. The laser structure of claim 10, wherein the laser source isformed in a region of the matrix of a first doping type and wherein atleast a portion of the plurality of vertical confining features areformed in one or more regions of the matrix of a second doping type. 18.A laser system, comprising: a laser source; and a waveguide opticallycoupled to the laser source, wherein the laser source comprises: amatrix formed of a first material; a laser source formed within thematrix and comprising a second, different material; and a plurality ofconfining features formed within the matrix and extending parallel toand along a length of the laser source, the plurality of confiningfeatures comprising the second material, wherein the plurality ofconfining features are formed on at least one of a plurality of sides, atop, and a bottom of the laser source, and wherein the plurality ofconfining features are configured to adjust a size and profile of a modeof the laser source to match a mode of the waveguide.
 19. The lasersystem of claim 18, wherein the plurality of confining features arearranged symmetrically relative to the laser source.
 20. The lasersystem of claim 18, wherein the first material has a refractive indexlower than a refractive index of the second material.